Allergic rhinitis is an inflammatory autoimmune disease that causes symptoms such as sneezing, itchy nose, difficulty breathing and/or runny nose (medical term: increased nasal discharge). It is a reaction to allergy-triggering airborne substances (medical term: aeroallergens) and, depending on the allergen, can cause seasonal or year-round symptoms.
Prevalence in children and adults
The disease commonly occurs in all age groups. It usually begins in childhood and remains for life.
According to the World Health Organization (WHO), around 400 million people worldwide had allergic rhinitis in 2007. Prevalence was highest in Europe with around one in four Europeans suffering from the disease. Many people – around 40% of the total population – become predisposed to allergies over time due to exposure of the mucous membranes to allergens (medical term: sensitisation). But not all sensitised people will experience actual allergy symptoms. This is referred to in medical terms as a latent allergy.
Causes and triggers
Experts believe that external factors such as tobacco smoke and environmental pollution in addition to hereditary factors could play a role in the development of the disease. There is currently no available research that explains why some people develop allergies while others develop only a latent allergy or none at all. Allergic rhinitis triggers include seasonal allergens such as pollen from trees, grasses or weeds, mould spores, and year-round substances such as house dust mites and animal hair.
In Germany, seasonal pollens such as birch, hazel, elder and ash are common, as are grass, mugwort and ragweed pollens. The pollen count and type of airborne allergens depend on factors such as the geographic region and whether the measurements are taken in rural or urban areas.
But how does allergic rhinitis develop in the body? During the sensitisation phase, the mucous membrane is exposed to an allergen, which activates specific antibodies for the first time, usually in the lymph nodes. At the same time, a series of additional processes is triggered in body’s the immune system. As a result, the body produces immune cells that specifically target this allergen and have surface structures allowing them to attach to this allergen.
If the body is now re-exposed to the allergen, these cells become active and bind to the allergens. For the immune defence to be effective, additional cells are activated that release inflammatory messenger substances including histamine and leukotrienes. These substances are what cause the classic symptoms of allergic rhinitis (e.g. swelling of the mucosa).
Symptoms mainly occur in the areas that come into direct contact with the pollen allergens – the mucous membranes of the nose, eyes and mouth. The following symptoms may occur:
- Nose: runny nose with watery discharge, stuffy nose, itchy nose, sneezing
- Eyes: conjunctival redness, itching, tearing
- Mouth/throat: burning, itching
- Ears: itchy ear canals
- Lungs: dry cough (especially at night), wheezing, shortness of breath (asthma)
- Skin: worsening of atopic dermatitis, in rare cases hives, redness
- General symptoms: tiredness, sleep disturbances, headaches
There is also the risk of developing “allergic march”, which occurs when allergic rhinitis progresses to asthma.
In certain cases, the doctor can diagnose the disease based on the patient’s history. The doctor asks the patient about his or her symptoms and any possible associations and analyses them (medical term: anamnesis). To make it easier to identify potential triggers, you can observe in advance when and in which context your allergic rhinitis occurs. A patient diary or a digital service such as the Pollen app can be useful for this. It is generally easier to diagnose the disease if the symptoms are seasonal or a single trigger can be clearly identified than if the symptoms are chronic or there are several potential triggers. In addition, some types of non-allergic rhinitis can cause similar symptoms and must therefore be excluded from the diagnosis.
In children, especially infants, the diagnosis can be challenging. Sometimes the only symptom is mouth breathing, which is caused by a stuffy nose. During the first years of a child’s life, it is difficult for parents to tell the difference between a viral respiratory infection and allergic rhinitis.
The physical examination usually includes the airways, throat, ears and chest. Various allergy tests, such as the skin prick test or blood test can also be performed to confirm the diagnosis.
The treatment of allergic rhinitis usually begins with anti-allergy medications called antihistamines. Many of these medications are available at pharmacies without a prescription and are therefore frequently taken by patients on their own. Because they are fast acting, they can be used whenever necessary. Antihistamines block the receptor sites of histamine in the body, thereby reducing the allergic reaction. These substances work quite quickly. However, first generation medicines can cause side effects such as tiredness and drowsiness. The newer antihistamines cause fewer side effects; tiredness and headaches rarely occur.
Other available treatments include corticosteroid or decongestant nasal sprays, anti-allergy eye drops and leukotriene antagonists (medications that reduce the action of leukotrienes).
Corticosteroid nasal sprays have an anti-inflammatory effect and suppress symptoms such as runny or stuffy nose. The medications usually start working after 12 to 24 hours and reach their full effectiveness after three to seven days. Modern corticosteroid nasal sprays only work locally and have no side effects in the rest of the body. Adverse effects such as dryness of the nasal mucosa, nosebleeds or headaches may occur. However, stunted growth has been reported in children and adolescents (due to the active ingredient beclomethasone dipropionate). Although this is not likely to occur, the long-term use of this medication should be regularly monitored by a doctor.
Leukotriene antagonists block the action of leukotrienes, which are substances that, like histamine, play an important role in (allergic) inflammation. They are used to treat asthma. They also are effective in treating allergic rhinitis (but less than antihistamine tablets), and are used as a second choice if the patient has both asthma and hay fever. Possible side effects include headaches, gastrointestinal disturbances and respiratory infections.
In some patients, medications do not sufficiently reduce symptoms. For these patients, the next step to consider is specific immunotherapy (SIT). The aim is to allow the immune system to become used to the allergen over a longer period of time; however, the exact allergen must be identified.
SIT can be performed in two ways. In traditional therapy, the allergen is injected into the layer of fat under the skin of the upper arm (medical term: subcutaneous) at specific time intervals and in increasing doses until a maintenance dose is reached. This therapy is carried out over several years and is most frequently used to treat a pollen or house dust mite allergy. Severe side effects have been observed more often in people who are allergic to animal hair; therefore SIT is rarely used to treat these patients and should be carefully considered.
In recent years, allergens in tablet or drop form have been developed for use in patients who are allergic to pollen or house dust mites. These preparations are given to the patient under the tongue (medical term: sublingual), where they are briefly held and then swallowed. This treatment can be carried out at home and also takes several years.
Neither subcutaneous nor sublingual treatment can guarantee that the allergy will disappear. But unlike treatment with medication, if SIT is successful, the effect lasts after therapy has been completed.
Immunotherapy may be an option for patients with severe symptoms that have persisted for more than two years. Young people who do not react to many different allergens have the best chances of success.
Unfortunately there are very few ways to treat the causes of existing allergies. The main goal is therefore to prevent them. You can find out how to prevent allergies here.
Living with allergic rhinitis
Allergic rhinitis tips
For more information on managing various allergies, please consult the everyday tips section:
- For people with pollen allergies: How can allergy symptoms be effectively reduced during pollen season?
- For people with mould allergies: How can I prevent mould growth in my home?
Dr. med. H. Lee, Dr. med. S. Khouw
Prof. Dr. med. M. Worm (V.i.S.d.P.), Prof. Dr. med. Dr. h. c. T. Zuberbier
Last changes made: April 2017